Elastic fibres in health and disease

Baldwin, Andrew K.; Simpson, Andreja; Steer, Ruth; Cain, Stuart A.; Kielty, Cay M.

doi:10.1017/erm.2013.9

Cited by 240 publications

(169 citation statements)

References 187 publications

(270 reference statements)

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“…The fibers consist of two major components: an amorphous elastin core surrounded by a sheath of fibrillin-rich microfibrils (2). Elastin is a highly hydrophobic polymer of the soluble precursor tropoelastin (3).…”

Section: Mfap4 (Microfibrillar-associated Protein 4)mentioning

confidence: 99%

Characterization of Microfibrillar-associated Protein 4 (MFAP4) as a Tropoelastin- and Fibrillin-binding Protein Involved in Elastic Fiber Formation

Pilecki

Holm

Schlosser

et al. 2016

Journal of Biological Chemistry

116

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MFAP4 (microfibrillar-associated protein 4) is an extracellular glycoprotein found in elastic fibers without a clearly defined role in elastic fiber assembly. In the present study, we characterized molecular interactions between MFAP4 and elastic fiber components. We established that MFAP4 primarily assembles into trimeric and hexameric structures of homodimers. Binding analysis revealed that MFAP4 specifically binds tropoelastin and fibrillin-1 and -2, as well as the elastin cross-linking amino acid desmosine, and that it co-localizes with fibrillin-1-positive fibers in vivo. Site-directed mutagenesis disclosed residues Phe 241 and Ser 203 in MFAP4 as being crucial for type I collagen, elastin, and tropoelastin binding. Furthermore, we found that MFAP4 actively promotes tropoelastin self-assembly. In conclusion, our data identify MFAP4 as a new ligand of microfibrils and tropoelastin involved in proper elastic fiber organization.Elastic fibers are key extracellular matrix structural elements of connective tissues that undergo repeated stretch, such as large arteries and the lung (1). The fibers consist of two major components: an amorphous elastin core surrounded by a sheath of fibrillin-rich microfibrils (2). Elastin is a highly hydrophobic polymer of the soluble precursor tropoelastin (3). Tropoelastin is known to undergo a self-assembly process known as coacervation (4), often believed to be a first step in the process of elastic fiber maturation. Because of the high content of lysine residues within the tropoelastin sequence, its assembly into a polymeric form is stabilized by formation of desmosine crosslinks, catalyzed by the lysyl oxidase (LOX) 3 enzyme family (5).Microfibrils, the other major component of elastic fibers, provide the structural scaffold for the deposition of elastin globules. They consist primarily of fibrillin-1 and fibrillin-2, large glycoproteins with a high degree of homology (6). Apart from fibrillins, numerous accessory proteins have been shown to associate with microfibrils or elastin and promote formation of mature fibers, including fibulins and microfibril-associated glycoproteins (MAGPs) (7-10). The importance of proper elastogenesis has been underscored by gene deficiency studies: mice lacking elastin, LOX, or fibrillin-1 die shortly after birth because of vascular abnormalities (11-13).MFAP4 (microfibrillar-associated protein 4) is an extracellular matrix protein belonging to the fibrinogen-related domain (FReD) family. The family includes several proteins engaged in tissue homeostasis and innate immunity, such as FIBCD1 (fibrinogen C domain-containing 1), ficolins, and angiopoietins (14 -16). The crystal structure of the FReD of several family members has been solved (17-19). The ligand-binding site, designated S1, is described in all the proteins and is located in close proximity to the calcium-binding site. MFAP4 has been reported to form homodimeric structures that further oligomerize, but its definite oligomerization pattern has not been established (20).MFAP4 is conside...

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Section: Mfap4 (Microfibrillar-associated Protein 4)mentioning

confidence: 99%

Characterization of Microfibrillar-associated Protein 4 (MFAP4) as a Tropoelastin- and Fibrillin-binding Protein Involved in Elastic Fiber Formation

Pilecki

Holm

Schlosser

et al. 2016

Journal of Biological Chemistry

116

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“…Studies suggest a pool of extracellular tropoelastin that is ultimately retained as an insoluble polymer in the extracellular matrix [32, 33]. This implies that a portion of the extracellular tropoelastin pool remains in the medium prior to cross-linking.…”

Section: Discussionmentioning

confidence: 99%

PKCε Increases Extracellular Elastin and Fibulin-5/DANCE in Dermal Fibroblasts

Nishizaki¹

2018

Cell Physiol Biochem

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Background/Aims: In the earlier study, the selective PKCε activator DCP-LA increased elastic fibres in the dermis of HR-1 hairless mice. As a process of elastic fibre formation, tropoelastin, an elastin monomer, is secreted into the extracellular space. Secreted tropoelastin is delivered to the microfibrils by fibulin-5/developmental arteries and neural crest epidermal growth factor-like (DANCE) and undergoes self-association. Then, tropoelastin assembles around the microfibrils, growing into elastin and elastic fibres by lysyl oxidase (LOX)- or LOX-like (LOXL)-mediated cross-linking. The present study was conducted to understand the mechanism underlying DCP-LA-induced increase in elastin/elastic fibre. Methods: Western blotting, immunocytochemistory, and real-time reverse transcription-polymerase chain reaction (RT-PCR) were carried out in cultured human dermal fibroblasts. PKCε, mammalian target of rapamycin complex (mTOR), and p70 S6 kinase (S6K) were knocked-down by transfecting each siRNA. Results: DCP-LA increased elastin and fibulin-5/DANCE in a treatment time (6-24 h)- and a bell-shaped concentration (1 nM-1 µM)-dependent manner in the culture medium of human dermal fibroblasts. DCP-LA markedly increased elastic fibres in the extracellular space of cultured fibroblasts. DCP-LA-induced increase in extracellular elastin and fibulin-5/DANCE was abolished by a PKC inhibitor or knocking-down PKCε. DCP-LA did not affect expression of mRNAs for tropoelastin and fiblin-5/DANCE in cultured fibroblasts. DCP-LA-induced increase in extracellular elastin and fibulin-5/DANCE was not inhibited by the protein synthesis inhibitor cycloheximide or by knocking-down mTOR and S6K. DCP-LA never increased extracellular elastin in the presence of elastase, that breaks down elastin. An inhibitor of matrix metalloproteinase 9, that degrades multiple extracellular matrix components including elastin, had no effect on the basal levels and the DCP-LA-induced increase levels of extracellular elastin. Conclusion: The results of the present study indicate that PKCε, activated by DCP-LA, increases elastin and fibulin-5/DANCE in the extracellular space of cultured fibroblasts by the mechanism independent of transcriptional and translational modulation or inhibition of elastolysis.

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“…Mature elastic fibers are composed of an elastin core surrounded by fibrillin microfibrils, with additional accessory molecules and glycoproteins that facilitate elastic fiber assembly and function. 37 Interestingly, neuraminidase 1 (Neu1) is required for elastic fiber assembly; Neu1-deficient fibroblasts exhibit impaired elastogenesis that is reversible upon addition of exogenous sialidase. During elastogenesis, the soluble precursor tropoelastin is chaperoned to the cell surface by elastin-binding protein (EBP).…”

Section: Discussionmentioning

confidence: 99%

Sialidase Unmasks Mucin Domain Epitopes of Lubricin

Solka

Miller

Schmid

2016

J Histochem Cytochem.

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SummaryLubricin is a secreted, mucin-like glycoprotein and proteoglycan abundant in synovial fluid that provides boundary lubrication and prevents cell adhesion in synovial joints. The antilubricin S6.79 monoclonal antibody recognizes an O-linked glycopeptide epitope in lubricin's mucin domain. The central, long mucin domain of lubricin is extensively O-glycosylated with Gal(β1-3)GalNAc-O-Ser/Thr, and about two thirds of the O-glycosylated sites are capped with sialic acid. Our aim was to determine whether removal of sialic acid by sialidase could improve the detection of lubricin in a number of human tissues using the S6.79 monoclonal antibody. Sialidase treatment caused a dramatic increase in antibody reactivity in human pericardium, splenic capsule and trabeculae, plasma, serum, eye sleep extract, and liver sinusoids. Sialidase had minimal effect on S6.79 antibody reactivity with lubricin in synovial fluid and synovial tissue. These observations suggest that the origin of lubricin in blood may be different from that in synovial fluid and that desialylation of lubricin is essential for unmasking epitopes within the mucin domain. (J Histochem Cytochem 64:647-668, 2016)

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Elastic fibres in health and disease

Cited by 240 publications

References 187 publications

Characterization of Microfibrillar-associated Protein 4 (MFAP4) as a Tropoelastin- and Fibrillin-binding Protein Involved in Elastic Fiber Formation

Characterization of Microfibrillar-associated Protein 4 (MFAP4) as a Tropoelastin- and Fibrillin-binding Protein Involved in Elastic Fiber Formation

PKCε Increases Extracellular Elastin and Fibulin-5/DANCE in Dermal Fibroblasts

Sialidase Unmasks Mucin Domain Epitopes of Lubricin

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